1. Field. This disclosure is concerned generally with blood preservation and especially with addition of agents for extended storage or treatment of blood components such as platelets and erythrocytes.
2. Prior Art. Blood Bag systems designed for the "closed" mixing of different materials such as liquid and solid components are known. See, for example, Kaufman et al U.S. Pat. No. 4,484,920 showing a system for the flow-through mixing of liquid and solid components. The system disclosed in that patent is designed primarily for the mixing of solid drugs in a diluent. The disclosed mixing system uses an internal compartment containing a solid material (e.g., a drug). The compartment has two access ports, one at each end. These ports permit a diluent to pass through the compartment and carry with it the solid for ultimate mixing in a final larger container. The system of the patent does not appear to be concerned with the preservation and long term storage of blood components or the sterilization of such systems. Instead, the patent appears to be concerned with the reconstitution of lyophilized drugs, especially those that are difficult to reconstitute into solutions.
Talcott U.S. Pat. No. 4,162,676 discloses the use of a Ca(OH).sub.2 -impregnated silicone insert within a blood bag to control pH. However, it is not clear whether that system could successfully withstand heat sterilization temperatures and provide a controlled amount of the buffer.
It is well known that the storage of certain blood components in plastic bags can be enhanced by providing certain chemicals in the storage solution. For example, the control of pH of platelet concentrates is critical to long term storage and the pH can be controlled with certain buffers such as bicarbonate salts in solution. See also, Deindoerfer et al. U.S. Pat. No. 3,874,384 and Talcott U.S. Pat. No. 4,162,676, cited above. Ideally, such compounds should be available in a "closed" blood bag storage system. In such a system, the collection of blood, its separation into various components, its storage, and ultimate infusion of a given component into a patient, occurs without opening the system to the possibility of outside contaminants. This can be accomplished using pre-connected multiple blood bags (connected by tubings) having externally manipulated valves, etc. Unfortunately, some materials or compounds that would be useful for the storage of blood components can not be sterilized while in solution without degradation. Hence, they must be added as outside agents to an originally closed system after heat sterilization, thus causing the system to be "open" or have an increased chance of contamination.
We have now found that a closed but sterilizable blood bag storage system can be made to include chemicals that would degrade if mixed with other materials or in aqueous solution under heat sterilizing conditions. Details of our system are disclosed below.